Drier felt for paper machines and the like



July 14, 1936.. w. A. BARRELL 2 DRIER FELT FOR PAPER MACHINES AND THE -LIKE Fild Sept. 21, 1955 a a /Z/6IH/ [PL/767W Zia! Patented July 14, 1936 UNITED STATES PATENT OFFICE DRIER FELT FOR PAPER MACHINES AND THE LIKE 10 Claims.

The present invention relates to drier felts of two ply woven construction for use, in the manner explained in the patent to W. L. Barrell, No. 636,482, November 7, 1899, to hold the damp newly made web of paper coming from a paper machine closely and smoothly against rotating steam heated metal drying drums, over and around which the Web passes until it has been dried sufficiently for calendering. It is the pur pose of the present invention to provide an improved drier felt having capacity for longer useful life than those heretoforemade; and having greater porosity, particularly in the back or outer ply, with improved provisions for conduction of moisture from the face to the back of the felt. These objects are accomplished by the novel construction of drier felt hereinafter described, and illustrated in the accompanying drawing.

In said drawing- Fig. 1 is a plan view of a fragment of my new drier felt as seen looking toward the face of the felt;

Fig. 2 is a longitudinal section taken on line 2-2 of Fig. 1;

Figs. 3 and 4 are cross sections taken on lines 3--3 and 4-4 respectively of Figs. 1 and 2;

Figs. 5-9 inclusive are diagrammatic views on a larger scale to show the construction more plainly, and represent the constituent strands of the felt as more widely separated than in the actual construction. of these, Fig. 5 is a face plan view, Fig. 6 a plan of the rear or under side, and Figs. 7, 8 and 9 are sections on lines 'l.-'l, 8-8 and 9-9 respectively of Fig. 5;

Fig. 10 is a section showing a variation in construction of the same invention.

Like reference characters designate the same parts wherever they occur in all the figures.

It will be assumed for the purpose of the present description, but without intent to limit the invention to a specific material, except in so far as the material here named may be essential to any of the purposes and objects of the invention, that all the strands of the felt are of cotton fiber and each is constructed of a number of single yarns twisted together to give adequate bulk and strength. I may use yarns of the same characteristics as are commonly used in the commercial felts manufactured under the said Barrell patent, or larger or smaller strands as desired.

The face ply of the felt is composed of structural, or body, warp strands a and b in repeated alternation, interwoven as a plain weave with filling strands c and c; the strands or ends a of the warp passing over the picks c and under the picks a of the filling, for instance, and the warp strands b passing under the picks c and over the picks Similarly the back or outer ply is a plain weave consisting of warp strands d and e, alternating with one another, and filling or weft strands f and f in alternation. The two plies of the fabric are tied together by binder strands g which run parallel with the body warp strands and pass back and forth over picks in the filling of the face ply and back ply alternately. For the purpose of illustration such binder strands are shown in Figs. to 8 as passing over the picks c of the face ply filling and under the picks f of the back ply filling. The number of binder strands and their disposition, that is, the manner in which they are interlocked with the filling strands of the two plies, may be varied in any manner suited to tie the two plies securely together. There may be as many binder strands as there are ends in the body warp of either ply; or more or fewer'binder strands.

The said binder warp strands g are woven under heavy tension, so as to pull them into the interior part of the fabric, so to speak, that is, mainly beneath the body warps; thus binding the two plies tightly together and preventing the binder threads from showing on either surface of the felt above either the body warp or the extra warp strands hereinafter described.

In addition to the above described structure, which constitutes the main part or body of the felt, I have provided an additional series of warp strands, which I may designate as extra or supplemental warp strands, in distinction from the body warp strands a, b and c, of. These supplemental warp strands are designated by the reference letter h. They lie for the greater part of their length on the outer surface of the upper or face ply of the felt, and substantially or nearly cover this surface. Therefore, and in order to anchor them securely and for other purposes also, each of the additional warp strands passes over a plurality of picks of filling in the face ply, thence under one pick of the filling in the back ply, and then over another series of filling strands in the face ply, and so on, overlying all the filling strands of the face ply but crossing under noncontiguous filling strands of the back ply. The body warp strands and additional warp strands may be provided in various proportions and interwoven in various ways, all within the scope of-the generic invention here claimed. The specific embodiment of the invention chosen for illustration herein is one of a variety of possible embodiments, and will now be described in detail.

In this design, the supplemental strands are equal in number to all of the body warp strands a and b of the face ply combined, and also to the body and warp strands d and e of the back ply combined, and they are placed in alternation with the body warp strands, so that each of the latter is flanked by two of the supplemental warp strands. Also each supplemental warp strand is formed with loops which pass each between two adjacent picks of the filling in the face ply and around single picks of the filling in the back ply; the picks c and 0 being embraced in pairs between such loops. All of the loops which pass through the back of the felt embrace the same picks of the back ply and leave the intermediate picks clear of engagement with any crossing strands except the body warps d and 6, thus increasing the porosity of the structure. As made commercially the felt of this design contains eight each of the body warp strands a, b, d and e, sixteen of the supplemental warp strands h, and sixteen of the binder strands per inch of width.

All of the body and supplemental Warp strands of the design now being described are so large, or conversely so numerous in proportion to their thickness, that they are closely crowded together. The supplemental warp strands are preferably equal in weight, thickness and density to the body warp strands; although they may be larger or smaller, denser or less dense. They are woven under relatively light tension, which is only enough to make them weave in successfully, and is much less than the tension applied to either the body warp strands or the binder strands g. In the course of weaving, the supplemental warp strands are held up by the harness during the placement and beating up of two picks of the filling in the face ply, and while the shed is changed after placement of each pick; and they are then brought to the back of the felt and passed around a single pick of filling in the back ply, together with half the warp strands of that ply. In consequence of these factors, those portions of the supplemental warp strands which overlie the filling strands of the face ply, also overlie the body warp strands of that ply to a considerable extent, and protrude beyond them, as shown by Figs. 3 and 4, forming a substantially or nearly continuous surface on the face of the felt; while in the back ply the strands of supplemental warp lie against and are locked in place by alternate filling strands of the back ply. The side which is thus referred to as the face of the felt is that which contacts with the paper, and is the only one which does so; and the supplemental warp strands h where they lie exposed on this surface are the only members of the felt structure which touch the paper. Thereby they take all the surface wear incident to the use of the felt, and form a protective covering for the main body on which the strength and life of the felt depend; and they insulate the main body to a considerable extent from the destructive effects of heat and moisture in the drying process.

These additional warp strands h lie so near together that they do not indent the paper to an objectionable extent; that is, they do not make so called felt marks too deep to be obliterated by calendering. But if desired, the surface constituted by these supplemental strands may be smoothed and flattened before use by any suitable finishing methods, such as calendering, etc. A considerable flattening of this character naturally takes place in the ordinary use of the felt. Flattening of the supplemental warps on the outer face of the felt also spreads them laterally so that they cover and fill to a more or less complete extent the interstices between them left in the original weave.

The binder warp strands g, being woven under heavy tension, as previously described, are largely covered, not only by the body warp strands, but further by the supplemental warp strands, also, so that they are very deep below the effective outer face of the felt and are afforded a maximum of protection against the destructive effects of the drying process.

It has previously been mentioned that the binder Warp strands may be arranged in. various ways, and in Fig. 10 I have shown an arrangement in which they are placed beside or in parallel with the supplemental warp strands at all points. In some respects it is preferable to arrange them in this manner rather than in the way first described, because the same harness can be used for both the binders and the supplemental warps. But the binder warps, being wound on a separate beam, may equally well be, and are, held under heavier tension, in any desired degree, than either the supplemental or the body warp strands of the felt. With such an arrangement the heavy weaving tension on the binder threads causes them to sink into the body of the fabric and to be completely covered by the supplemental strands h on both the face and back of the felt, and thereby protected by the supplemental warps.

As the forces tending to separate the plies are in some cases negligible in terms of tensile strength, it is permissible in such cases to omit the binder threads 9 and allow the extra warp strands h to act as binder elements as well as performing their main function, previously described, of forming an extra surface and protective covering over the main body of the felt. Thus it would not be a departure from the broader aspects of the invention here claimed to omit the binder threads 9.

A felt having the construction and characteristics herein described, and woven otherwise according to the practice used in making commercial two ply felts, has conspicuous utility and advantage over prior constructions. It eliminates a large proportion (in this particular case half) of the number of ends of body warp heretofore used in two ply felts made of the same size strands, and this without making the structure unduly loose or liable to become too narrow in service. The large supplemental warp strands, which are substantially as dense and hard twisted as the body warp strands, and may be more so, cross between each two of the latter and tie in every alternate filling strand of the back ply at all crossing points, and so provide as much resistance to narrowing of the felt under tension as would have been given by the omitted body warp strands.

It is more porous, due largely to the open construction of the back ply in which open spaces are left between the body warp strands across and beside each of the filling picks 1 which are not embraced by a binder. Also spaces exist in the face ply wherever a supplemental warp strand h passes over a pick of the filling while the adjacent body warp strand passes under the same pick. One of such spaces is designated by the numeral l in Fig. 5 where a supplemental warp strand h passes over, and a body warp strand 1) passes under, a pick 0 of the filling, and another one is designated at 2 where a parallel supplemental warp strand passes over, and a body warp strand a passes under, the next adjacent pick 0' of the filling. These spaces facilitate escape of water vapor from the paper being dried. In so far as the supplemental warp strands are absorptive of water, their loops which pass through the back ply and around the picks thereof serve as conductors to lead water by capillary action to the exposed back of the felt where evaporation removes the moisture into the air of the room.

The supplemental warp strands h on the face of the fabric prevent the body warp strands of the face ply from coming into contact with the hot damp paper, and thus protect these warp strands from the wear and tear incident to service, and protect as well both the face, back and binder warp strands from the destructive effect of high temperature. Thereby the body warp strands of the face ply retain their strength and take their part of the load in pulling the felt around the drums and guide rolls of the drier for a longer time than would otherwise be the case. Even though the strength of those parts of the supplemental warp strands which lie on the face of the felt be utterly destroyed, this does not diminish their serviceability, for they are not relied on in any degree to lend tensile strength to the felt, and they are not put under tension by the strain which is applied to the felt when running. Even in those special cases where the regular binder threads 9 are omitted and the supplemental warp strands h are relied on to act as binders in addition to their protective function, the complete burning or rotting of those parts of the strands h which lie on the face of the felt would not destroy the tying function because those parts of the supplemental strands which pass through the felt from front to back are protected, and are so gripped by the body warps on opposite sides of them, somewhat as a nail driven into a board is gripped by the fibers of the wood, that they are still serviceable and able to perform their connecting or tying function against the negligible force tending to separate the plies.

It is to be understood, however, that considerable variation may be made in the construction with retention in whole or in part of the before mentioned advantages. Thus, since the resistance to narrowing of the felt is mainly a function of the sum total of strands crossing the filling of the face warp, and the density and close propinquity of such warp strands, similar effects may be accomplished by providing more body warp strands in the face ply than there are either of supplemental warp strands or body strands in the back ply. The supplemental warp strands, when fewer in number than the body warp strands of the face ply, may be made relatively softer, and larger if desired, in order to cover the face of the felt to the extent needed for the desired protection.

While I have herein described the felt as being made entirely of cotton strands, I wish to make it understood that I am not limited to cotton as the material of all or any of the strands, but may use other materials suitable for the purpose. Such suitable materials are any which have adequate strength and pliability, including not only those which have been used in drier felt manufacture heretofore, but others which may by test and experience be hereafter found satisfactory. Strands or fibers of such other suitable materials may be combined with cotton strands or fibers, or with one another, as either the body warp or the filling of either or both plies, or fo the supplemental or extra warp strands.

It is to be understood that the scope of my claimed protection embraces the drier felt in all uses which it is adapted to serve.

What I claim and desire to secure by Letters Patent is:

1. A drier felt for paper machines comprising two plies constructed each of interwoven body warp and filling strands, binder strands interwoven with body strands of both plies and supplemental warp strands equal in number to all of the body warp strands of either ply, each passing over all the filling strands of the face ply and having loops passing between all the body warp strands of both plies and being interlocked with filling strands of the back ply as originally woven; the parts of the supplemental warp strands which lie in the paper-contacting face of the felt being supported by the contiguous body warp strands so that they protrude beyond said body strands in said paper-contacting face.

2. A drier felt for paper machines comprising two plies constructed each of interwoven body warp and filling strands, binder strands passing back and forth between said plies and around body strands of both plies in alternation, tying them together, and supplemental warp strands extending along the outer face of one of the plies, overlying all the filling strands of such plies and substantially overlying the body warp strands also of the same ply as originally woven and without distortion by fulling, whereby they constitute the paper-contacting portion of the felt and protect the body warp strands from wear and from the destructive effects of heat and moisture in the use of the felt.

3. An unfulled drier felt for paper machines comprising two plies constructed each of interwoven body warp and filling strands, binder strands passing back and forth between said plies and around body strands of both plies in alternation, tying them together, and supplemental warp strands extending along the outer face of one of the plies, overlying all the filling strands of such plies and substantially overlying the body warp strands also of the same ply, whereby they constitute the paper-contacting portion of the felt and protect the body warp strands from wear and from the destructive effects of heat and moisture in the use of the felt; said supplemental warp strands having loops at intervals in their length passing between adjacent body warp strands of both plies and around picks of the filling in the back ply, providing conductors for moisture from the face to the back of the felt.

4. An unfulled drier felt for paper machines comprising a face ply constructed of interwoven body warp and filling strands, a back ply constructed of an equal number of body warp and filling strands, binder strands, finer than said body strands, interwoven with body strands of both plies, and supplemental warp strands equal in numb-er to all of the body warp strands in either ply; said supplemental strands extending in parallel with one another over a plurality of filling strands of the face ply, then through the felt between each two adjacent body warp strands of both plies, and around a single filling strand of the back ply, then through the felt again and over the next plurality of filling strands of the face ply, around a contiguous filling strand of the back ply; and so on throughout the length of the felt, said body and supplemental warp strands being so closely crowded together that those parts of the supplemental strands which cross filling strands of the face ply protrude beyond the body warp strands of that ply.

5. A non-fulled drier felt for paper machines comprising two plies of interwoven body warp and filling strands, of which the filling strands run in substantially straight lines from side to side of the felt, the number of which per unit of area is the same in both plies, supplemental warp strands equal in number to the body warp strands of either ply, and binder strands or threads interwoven with the filling strands of both plies; said binder strands being smaller than the body warp strands and woven under greater tension, and the supplemental warp strands being of substantially the same size and weight as the body warp strands and woven under lighter tension, whereby the binder strands are drawn beneath the faces of the felt while the supplemental warp strands are laid mainly outside of the body warps on one face of the felt.

6. A non-fulled porous drier felt for paper machines comprising two plies each constructed of interwoven body warp and filling strands, binder strands interwoven with filling strands of both plies and lying mainly beneath the body warp strands, and supplemental warp strands lying outside of the body warp strands on the side of the felt which comes next to the web of hot damp paper being dried and having loops passing through the felt between successive groups of filling strands of the face ply, each between two contiguous body warp strands of both plies, and around noncontiguous filling strands of the back ply.

'7. A non-fulled porous drier felt for paper machines comprising two plies each composed of body warp and filling strands, binder Warp strands interwoven with filling strands of both plies and lying mainly beneath the body warp strands of said plies, and supplemental strands passing in parallel each over two picks of filling in the face ply and mainly outside the body warp strands on the side of the felt which in use contacts with the web of hot damp paper being dried, thence between two contiguous filling strands of the face ply and around a single adjacent filling strand of the back ply, thence around the next two filling strands of the face ply and under a third filling strand of the back ply; and so on throughout the length of the felt.

8. A drier felt for paper machines as set forth in claim 7, and in which the supplemental warp strands are equal in number to the body warp strands of each ply and those parts thereof which pass through to the back ply are interspersed between each two body warps of both plies.

9. A drier felt for paper machines comprising two plies of interwoven body warp and filling strands, the number of which per unit of area is the same in both plies, binder strands interwoven with the filling strands of both plies, and supplemental warp strands also interwoven with the filling strands of both plies; said binder strands being smaller than the body warp strands and woven under such tension that they are sunken below the outer surfaces of the felt, and said supplemental warp strands being of substantially as great cross section as the body warp strands and woven under such tension that they are laid mainly outside of the body warp strands on the outer face of one of said plies, and are further so woven as to provide loops at intervals which pass between contiguous filling strands of the last named ply and around an adjacent filling strand of the other ply.

10. A drier felt as set forth in claim 9 in which the said loops of the supplemental warp strands are separated from one another longitudinally of the felt by at least twice the distance between contiguous filling strands.

WILLIAM A. BARRELL. 

